World golf had barely cleared its throat in acclaiming Rory McIlroy as the game's most coruscating star when Jordan Spieth entered the picture, humble as you please, lethal as you like.

Twenty one years old - 22 later this month - and already Spieth has a place in the pantheon. Only five players in the history of golf have won the first two majors of the year in the four-major era.

Ben Hogan did it in 1951 at the age of 38 and again two years later. Arnold Palmer followed him into the annals in 1960, at 30. Then it was Jack Nicklaus in 1972, aged 32. And after that, Tiger Woods, just a 26-year-old pup when he took the Masters and the US Open in 2002.

The fact he took five years fewer than Woods to do it is remarkable given the other-worldly nature of Woods in his prime.

In terms of exclusive clubs, the first-two-majors-club takes some beating. Locked outside: McIlroy and Mickelson; Ballesteros and Faldo; Player and Watson; Trevino and Snead.

Not so long ago we were talking of Woods like he was something that might never be seen again in a lifetime, but here we are in a relative blink of an eye talking about a boy out of Texas going for three major championships in a row.

(From left) Ben Hogan, Arnold Palmer, Jack Nicklaus, and Tiger Woods are the only other men to have won the first two majors of the year. Only Hogan to date has gone on to win the first three, in 1953

The other day, at the Scottish Open at Gullane, Graeme McDowell spoke of what we might call it if Spieth wins the Open at St Andrews and wins again at the USPGA at Whistling Straits in August.

"You've got Jordan going for three in a row at the Open," said the Northern Irishman. "I've read people talking about the Spieth Slam. I'm not into Spieth Slam. I don't like it. It's not the Spieth Slam. It would be the Grand Slam.

"There was the Tiger Slam, the overlap [in 2001], but this would be the Grand Slam. This is the opportunity."

The fact that McDowell is talking about it as if there's a realistic chance of it happening just shows what kind of impact Spieth has made. It's mind-altering stuff.

In his young life, Spieth has played the princely total of one round at St Andrews and it was four years ago when he was a teenage amateur.

He doesn't know what it's like to play there in the heat of competition, he hasn't got an angle on the unpredictable winds or the vast greens. He will have known little of the idiosyncratic nature of the Old Course until he got there on Monday and yet the leading 16 bookmakers in the country all make him favourite to win the Claret Jug.

Such an approach would sound bonkers coming from most players, but not from Spieth. The kid is white hot. Since missing the cut at the Players' Championship in May he's won the US Open, has finished second at Colonial and third at Memorial.

In his past 20 competitive rounds - including the torture chambers of the US Open - he's an aggregate 56 under par. His putter is not so much a stick as a wand, a thing that magics up birdie after birdie from ever-increasing distances.

It's a long way from the Scottish Open to the John Deere, but Spieth's name was much-mentioned at Gullane. The business of the simulator and what benefit it might be, his lack of knowledge of St Andrews and how it might hurt him, the prospect of three-out-of-three. Issues everywhere. As far as Spieth goes, the fascination is endless.

Can Spieth win at St Andrews? The players' view

Ian Poulter (Eng)

"He's the best putter in the game right now. If you're the best putter and you play OK, you're going to have half a chance, aren't you?"

Matt Kuchar (US)

"He doesn't have weaknesses. That's the amazing thing. You can't see any flaws in his game or his mentality."

Stephen Gallacher (Sco)

"If the wind changes it's going to be tough to adapt but Jordan is number two in the world. He's young but he's old in golfing terms. He's won two majors, he knows the score."

David Duval (US)

"If you're playing well you can play anywhere, regardless of the nuances and intricacies of the golf course… Jordan has proven he has all the tools to win anywhere."

Paul Lawrie (Sco)

"These guys are so good it doesn't matter whether he's played it or not. One practice round is plenty. The wind won't make any difference. I can't see anything hurting him."

Sandy Lyle (Sco)

"He's a very level-headed guy, putts extremely well and it's all about who putts well. I wouldn't be amazed if he won… his momentum is so good right now. He's the real deal."

Graeme McDowell (NI)

"I think he could get it done. It's a bomber's course to a certain extent where they can blow it past trouble, but also a tactician's course. He's obviously a pretty fast learner."

"I've got a simulator and they're amazing," said Ian Poulter. "I use the same simulator that Jordan uses. They're very good from a visual standpoint, but there's nothing like the real thing. You obviously can't putt on them and you can't judge the wind. I've never seen a simulator blow, have you? There is no proper preparation apart from playing, but I can tell you Jordan will be there or thereabouts."

Phil Mickelson, the 2013 Open champion, also down-played the potential obstacles awaiting Spieth. "There's nothing like playing St Andrews, but I think if you spend two days there with a pretty intense work ethic you'll figure it out right away," he said. "I don't think it will take you forever. The problem is if the wind changes, then it will play totally different."

St Andrews, according to Rickie Fowler, "is probably one of the courses where course knowledge pays off the most". And yet such is Spieth's adaptability, the overwhelming view among his fellow pros is that the young man will find St Andrews to his liking.

"What an opportunity he's got to win again," said 1999 Open champion Paul Lawrie. "Why not? There's pressure on him but there was pressure on him to win the US Open and he looked great when he got his chance."

Woods has said he was "shocked" at how green St Andrews looked. Bone dry a month ago, the combination of rain and sunshine has changed it completely. It's now lush and soft instead of the fast-running track that Woods won on in 2000 and 2005.

That's in Spieth's favour as well in a sense. If the course is different to how the field have played it before then their advantage over the newcomer is reduced.

In golfing heaven, even Old Tom's whiskers will be fairly twitching if the Texan can win on Sunday. They like to think they've seen it all at St Andrews, but Spieth lifting the Claret Jug and moving to within one of a Grand Slam would be a story to match anything ever seen in the most storied town in the game.

Spieth equalled the lowest winning score in Masters history of 18 under par

Speith was the youngest player to win the US Open since Bobby Jones in 1923